Art historian Amy Knight Powell details the genealogy of the box as a frame, a window, and a container in art. She writes:

In “The Crisis of the Easel Picture” (1948), Clement Greenberg compares the easel picture, disparagingly, to a box-like cavity cut into the wall. In this essay, I argue that late medieval panel paintings—which indeed often took the form of boxes—show Greenberg to be justified in making this comparison, if not in doing so disparagingly. But what Greenberg failed to fully acknowledge is that the easel picture had already long tried to escape this condition through the opening of the metaphor of the window. Failing to recognize this earlier effort to escape the material conditions of the box, many modernists and postmodernists, like Greenberg, attempting to move beyond the easel picture in the name of an art undivided from life, have unintentionally upheld the easel picture’s own escapist ideology.